In which language are the Java compiler and JVM written?

Question

In which languages are the Java compiler (javac), the virtual machine (JVM) and the java starter written?

Answer 1

• When Java is introduced by Sun Microsystem, the java compiler was written in C using some libraries from C++.
• As There is a concept in Compiler Design called Bootstapping, Mostly it is used in Compiler Development, Bootstrapping is the process of writing a compiler(Or Assembler) In the source programming language which it is intended to compile. It is used to produce a self-hosting compiler. The development of compilers for new Programming languages first developed in an existing langauge and then rewritten in the new language and compiled by itself. That's why today, Java compiler is written in Java itself.
• Java Virtual Machine: Java virtual machine is an abstract machine. Like a real computing machine, It has an instruction set and manipulates various memory areas of run time.Usually JVM interprets the byte code into Machine code.

(For More Information You can check this link : https://docs.oracle.com/javase/specs/jvms/se7/html/)